Hearing assistance devices, such as hearing aids, process sound played for a user of the device. For example, hearing aids can have programmable gain (amplification) which is adjusted to address the hearing impairment of a particular user of the hearing aid. However, excessive gain can result in acoustic feedback. Acoustic feedback is the whistling or squealing occurring when sound from the receiver of the hearing aid is received by the microphone of the hearing aid. Therefore, it is important to know how much gain can be applied before acoustic feedback occurs. This is known as “maximum stable gain.” The maximum stable gain of any amplifier is typically a function of frequency. Therefore, to an audiologist or other person fitting a hearing aid to a particular user, it is valuable to have knowledge of maximum stable gain for any given band or frequency to best program the hearing aid for its wearer.
There is a need in the art for an improved system for measuring maximum stable gain in hearing assistance devices.